A heat exchanger

ABSTRACT

A heat exchanger in which wherein a first fluid flows through heat-exchanging tubes and a second fluid flows around the heatexchanging tubes, one of these fluids being a cooling fluid which withdraws heat from the other fluid, the cooling fluid being a gas supersaturated with water. The cooling fluid is supplied by a device for supersaturating a gas, in particular air, with water.

United States Patent van Diepenhroek Sept. 18, 1973 A HEAT EXCHANGERInventor: Alfred Erich Wibrandt van Diepenbroek, Ermelo, NetherlandsAssignee: N.V. Bronswerk Apparateubouw v/h Moring & Steenaart, Nijkerk,Netherlands Filed: Aug. 5, 1971 Appl. No.2 169,268

Foreign Application Priority Data Aug. 10, 1970 Netherlands 7011801 us.(:1 165/19, 165/60, 165/122 Int. Cl F24f 3/14 Field of Search 165/1, 19,20, 60,

[56] References Cited UNITED STATES PATENTS 2,129,427 9/1938 Jepertinger165/20 2,488,636 11/1949 Mendenwall et al. 165/20 PrimaryExaminer-Charles Sukalo Att0rney-Erich H. Waters et al.

57 ABSTRACT A heat exchanger in which wherein a first fluid flowsthrough heat-exchanging tubes and a second fluid flows around theheat-exchanging tubes, one of these fluids being a cooling fluid whichwithdraws heat from the other fluid, the cooling fluid being a gassupersaturated with water. The cooling fluid is supplied by a device forsupersaturating a gas, in particular air, with water.

3 Claims, 2 Drawing Figures Patented Sept. 18, 1973 A HEAT EXCHANGERBACKGROUND OF THE INVENTION The invention relates to a heat exchanger inwhich wherein a first fluid flows through heat-exchanging tubes and asecond fluid flows around the heat exchanging tubes, one of these fluidsbeing a cooling fluid which withdraws heat from the other fluid.

According to a first known method, a cooling gas, generally outside air,is used as the cooling fluid, the other fluid being lowered intemperature via the wall of the heat-exchanging tubes and/or, if acondensable gas is involved, is condensed as a result of the dissipationof heat.

In this known method the cooling capacity is closely related to thetemperature of the cooling gas, i.e., to the temperature of the outsideair.

If the required final temperature of the fluid to be cooled difiers onlyslightly from the temperature of the outside air, the heat exchanger tobe used will have to have particularly large dimensions, which, however,is highly uneconomical and will not be feasible in many circumstances.

In these latter cases use is generally made of a further known methodwherein cooling water is used as the cooling fluid. This, however,substantially raises the operating costs of the installation, and is notvery desirable from the point of view of pollution control.

In view of these drawbacks, use is also made of yet another known methodusing cooling air which is first passed through a layer of fillermaterial wetted with water, causing the temperature of the air to dropto a value several degrees above the wet bulb temperature.

Although some improvement can be achieved in this manner, the decreasedsize of the heat exhanger to be used generally does not outweigh thecosts and the necessary additional space inherent in these arrangementsfor obtaining a decrease in the temperature of the cooling air.Accordingly, atmospheric air or water has been used almost exclusivelyas the cooling fluid.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a heat exchanger which offers substantial advantages as comparedto those specifically of a relatively very small size.

To this end, the invention is characterized in that a gas supersaturatedwith water is used as the cooling fluid.

The invention specifically proposes the use of a cooling fluidconstituted by air supersaturated with water.

A gas supersaturated with water, and specifically air supersaturatedwith water, contains appreciably more water than the amount of watervapor contained in the gas, specifically air, at 100 percent relativehumidity at the same temperature. The excess water forms a mist which isso finely divided as to follow the flow of gas (air) entirely.

Not only does the supersaturation with water cause the inlet temperatureof the cooling gas to be lowered, but it causes this lower cooling-gastemperature to be maintained for a longer period of time.

Further, it has surprisingly been found that the coeffi cient of heattransfer between the cooling gas supersaturated with water, generallycooling air supersaturated with water, and the heat-exchanging tubes isappreciably increased due to the presence of the mist of water.

The probable cause of this phenomenon is an evaporation in this mist ofwater resulting from the flow of the cooling gas along theheat-exchanging tubes, producing such turbulence in the immediatevicinity of the heat exhanging tubes as to break the boundary layer,thus removing the adverse effect thereof upon the coefficient of heattransfer.

According to the invention, the size of the heat exchanger can besubstantially reduced, resulting in great savings of costs and floorspace, while a lower final temperature of the fluid to be cooled can beattained.

Furthermore, on account of the small size of the heat exchanger, thedanger of freezing occurring in the known air-cooled heat exchangers isgreatly reduced.

This heat exchanger is characterized in that the cooling fluid issupplied by means for supersaturating a gas, in particular air, withwater.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will hereinafter befurther explained with reference to the drawing, which shows anembodiment of the heat exchanger according to the invention, by way ofexample, and wherein:

FIG. 1 is a longitudinal section of an embodiment of the heat exchangeraccording to the invention; and

FIG. 2 is a cross section taken on line IIII in F IG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT The drawing shows a heat exchangercomprising a purality of heat exchanging tubes 1, which bear outer ribs2, mounted in a frame 3. This frame 3 comprises a supply distributionchamber 4 and a discharge chamber 5 therebelow on one side and areversing chamber 6 on the opposite side.

The fluid to be cooled and/or to be condensed passes through theinlet 7into the supply distribution chamber 4 and flows through the upper rowof heat-exchanging tubes 1, whereupon the direction of flow is reversedin the reversing chamber 6 and the lower row of heatexchanging tubes 1is traversed. The cooled and/or condensed fluid then reaches thedischarge chamber 5 and is discharged through the outlet 8.

The frame 3 is supported by posts9 and is connected at its lower end toa funnel-shaped receptacle 10 which has an opening 11 in its bottom,wherein are positioned the outlets of two atomizing blowers 12 forsupersaturating air with atomized water. These blowers 12 are mountedside by side and may be of the type, for example, as described inBritish Patent Specification No. 750,559.

The atomizing blowers 12 are each driven by a belt 13 from an electricmotor 14. The outside air is sucked, through intake openings 15 locatedon either side of each atomizing blower 12, into the blowers 12, wherethe air is supersaturated with water. To this end, water is sprayedunder pressure through sprayers 16 disposed at the intake openings 15 ofthe blowers 12. This water is broken up to form a fine mist due to thespecial design of the impeller and the use of further provisions made inthe blower casing. This mist is entrained by the current of air thatemerges from the atomizing blowers 12. The water is fed to the sprayers16 from a pipe 17 which contains a control cock 18. The water not takenalong by the current of air can be drained from the atomizing blowers 12through outlet pipes 19.

Of course, use may be made of other devices for supersaturating air withwater. Examples of these include atomizing sprayers based on centrifugalforce, pressure-atomizing systems, or electrical vaporizing systems.

The supersaturated air flows around the heatexchanging tubes 1, causingheat to be withdrawn from the fluid to be cooled which flows through theheatexchanging tubes 1.

The outside air which is supersaturated with water possesses atemperature equal to the wet bulb temperature, which it retains for aprolonged period of time, despite the absorption of heat via theheat-exchanging tubes 1, because the mist of water evaporates in wholeor in part. The presence of the mist of water in the cooling airfurthermore produces an increase in the coefficient of heat transfer, asexplained hereinabove.

The absorption of heat by the supersaturated air while passing aroundthe heat-exchanging tubes 1 can be very simply controlled by adjusting,with the aid of the control cock 18, the amount of water supplied perunit time, and thus the degree of supersaturation of the cooling air.The heat exchanger can thus be adapted to the prevailing load.

The heat exchange can furthermore be regulated by changing the supply ofair to the atomizing blowers 12, for example with the use of valves, orof whirl control, or of an adjustment of the speed of rotation of theimpeller.

The supply of the fluid to be cooled to the inlet 7 naturally can alsobe made adjustable by using a bypass with an adjustable passage.

A small portion of the water entrained by the cooling air can falldownwardly during the passage of the cooling air from the atomizingblowers 12 to the heatexchanging tubes 1 as well as in the course ofpassing these heat-exchanging tubes 1. In such case, this water iscollected in the funnel-shaped receptacle and is fed back to theatomizing blowers 12, where the water can flow away through the outletpipes 19. Where required, the water discharged through the outlet pipes19 can be recirculated at least in part. Also, at least part of thecooling air, having passed the heatexchanging tubes 1, can be collectedand recirculated.

The invention is not restricted to the embodiment illustrated in thedrawing, which may be varied in different manner within the scope of theinvention. It is possible, for example, to use only one atomizing blower12, or more than two atomizing blowers, while the heatexchanging tubes1, which are horizontal in the embodiment shown, can also be arranged invertical or inclined positions.

Further, the supersaturated air can flow through rather than around theheat-exchanging tubes 1, in which case these heat-exchanging tubes 1 arepreferably provided with internal ribs. in such case, the fluid which isto be cooled flows around the heat-exchanging tubes 1.

I claim:

1. A heat exchanger, comprising heat-exchanging tubes, means forsupplying a first heated fluid to said tubes for flow therethrough,means for circulating a second cooling fluid around said heat-exchangingtubes, the means for supplying said cooling fluid including means forsupersaturating air with water including means for inducing a flow ofair to said tubes and means for finely dividing the water to follow theflow of air entirely, said means for inducing a flow of air to saidtubes comprising a blower having air inlets at opposite ends thereof andan outlet facing said tubes, said means for finely dividing the watercomprising sprayers located at said inlets and facing inwardly into saidblower for spraying the water under pressure thereinto, said blowerincluding an impeller facing said sprayer to break the water into a mistwhich is entrained in entirely in the air in superstiturated state.

2. A heat exchanger according to claim 1 wherein said air supersaturatedwith water flows around the heat-exchanging tubes, and comprisingdrainage means for water located below the means for supersaturating airwith water.

3. A heat exchanger according to claim 1 wherein the means forsupersaturating air with water comprises a control member for regulatingthe supply of water.

1. A heat exchanger, comprising heat-exchanging tubes, means forsupplying a first heated fluid to said tubes for flow therethrough,means for circulating a second cooling fluid around said heat-exchangingtubes, the means for supplying said cooling fluid including means forsupersaturating air with water including means for inducing a flow ofair to said tubes and means for finely dividing the water to follow theflow of air entirely, said means for inducing a flow of air to saidtubes comprising a blower having air inlets at opposite ends thereof andan outlet facing said tubes, said means for finely dividing the watercomprising sprayers located at said inlets and facing inwardly into saidblower for spraying the water under pressure thereinto, said blowerincluding an impeller facing said sprayer to break the water into a mistwhich is entrained in entirely in the air in superstiturated state.
 2. Aheat exchanger according to claim 1 wherein said air supersaturated withwater flows around the heat-exchanging tubes, and comprising drainagemeans for water located below the means for supersaturating air withwater.
 3. A heat exchanger according to claim 1 wherein the means forsupersaturating air with water comprises a control member for regulatingthe supply of water.